(CNN) -- Could George W. Bush or some of his top aides end up behind bars?

George W. Bush could be investigated for the steps taken after 9/11.

It's extremely unlikely, but the Obama administration is taking its first steps along a path that could lead in that direction, with the investigation of Central Intelligence Agency interrogators involved in the war on terror.

"You don't know where these things are going to end up," former CIA agent Peter Brookes told me. "They could go to very high levels in the government."

The probe will focus on whether interrogators exceeded their instructions and broke the law when, for example, they choked a prisoner until he lost consciousness or threatened another one with a gun and a power drill.

There is no obvious enthusiasm in the Obama administration for second-guessing the CIA's efforts after September 11, 2001 to keep America safe.

President Obama has said several times he wants to "look forward, not back."

Republicans immediately criticized the new investigation and even some Democrats said it would be unpopular.

"This is not very good politically for the administration," said Democratic strategist James Carville. "The public clearly doesn't have much of an appetite for this."

But Attorney General Eric Holder said evidence of abuses was compelling enough to require it. No one knows what other evidence will ultimately compel the administration to do.

The American Civil Liberties Union, an activist organization that campaigns against prisoner abuse, says "any investigation that truly follows the facts where they lead would inevitably lead to prosecutions of high government officials,"

Does it sound far-fetched?

One Bush administration legal advisor, Jack Goldsmith, says his colleagues were acutely conscious that the president or his advisors could someday be investigated for the steps they took or approved after 9/11.